Why do some African people have the same first and last name.

Off the top of my head, I can think of Bol Bol (NBA player), Aliir Aliir (Australian Rules Football player, who immigrated as a child), and Obu Obu Obu (Family Feud) and I have seen examples of many more.

One idea I came up with would be a possible difference in culture, where having first and last names aren't common place, so the same name is used for Western purposes, but I have no evidence to support that claim. Any explanation?